How to Add a Cat Door and Train Your Cat to Use It

Cat doors are a fixture of just about every cat-focused form of media. Whether you're watching your beloved fur baby sneak in and out at their leisure or a funny internet video of a cat getting stuck in a door, the humble cat door is a common sight in many cat-focused homes.

If you're interested in adding a cat door, it's important to go about it the right way and make sure your cat knows how to use it. So, let's talk about it!

Cat Doors and the Great Outdoors

The first thing I need to talk about, before we get any deeper into this topic at all, is how you should use a cat door.

Most people think of a cat door as a door in, well, your home's door, allowing your cat to slip inside and outside at their whim. It's handy for cats that are former outdoor cats and who beg to be let out all the time; that's really not a good thing.

As you likely know from reading other posts on this blog, I'm not a fan of outdoor cats or indoor-outdoor cats, at least not without strict supervision. Unsupervised cats can end up with all sorts of health issues, ranging from parasites to injuries from encounters with wildlife and other cats to diseases or poisonings. They also do a ton of damage to the local bird population, and who doesn't love listening to the songbirds?

That's all not to mention the human threats. There are people who get really, really mad at uncontrolled cats doing their business in the garden and people who are just inhumane and armed. Cars, too, are a constant threat. As much as we might not like to admit it, not everyone loves cats as much as we do, and people can be cruel.

Even without intentional threat, sometimes a well-meaning person might see your cat hanging out on their porch and decide to capture them, or let them in and feed them, or bring them to a local shelter or vet on the assumption that they're a stray.

Really, it just all causes a lot of hassle, stress, and pain.

So why am I writing a cat door article? Why don't I just call them bad and move on?

Because cat doors aren't strictly for the outdoors. You can install a cat door on any door you like of any size. You can put a cat door in a board across a window for a window-mounted catio, or in the front door to a screened-in porch, or just between rooms. A cat door in a bathroom door can ensure you have privacy from other people, but your cat can come in and do their business, too, if that's where you keep the litter boxes.

There are good uses for a cat door. I just really, really, really recommend not putting one in a door that leads to the outside. If you want your feline fur baby to experience the great outdoors, train them to tolerate a harness and bring them out supervised, where they can't get into trouble.

The Pros and Cons of Cat Doors

Cat doors have one major benefit, which is the ability to allow a cat to pass through a closed door while making sure whoever or whatever is closed off by that door is kept out or in. For example, if you have a large dog, a cat door can allow for free passage for your cat but keeps the dog stuck behind it, which gives your cat a way to retreat if the dog is too much for them or just lets you keep the dog out of the way while friends are over, but the cat can come and go.

There are, however, distinct pros and cons to using a cat door as opposed to just leaving a door open or manually opening and closing it as necessary.

First, the pros.

• It's freedom of movement for your feline friend when you aren't around or available to grant them passage while still restricting access to anything larger.
• It helps ensure your cat can have enrichment, whether it's fresh air, a catio to watch the birds or just access to another room where they can play and alleviate their boredom.
• It can be a place of safe haven for your cat to use to get away from noisy people, dogs, children, or other sources of stress.
• It can be a source of refuge. If you have to let your cat in and out of a catio or sunroom, if they get stuck in and forgotten or overlooked, they can overheat, dehydrate, or even suffer heat stroke.
• It can be a way to keep something unsavory, like a litter box, behind closed doors while still allowing free access to your cat. This is an added bonus if you have a dog that likes to dig for treasures.

These are some pretty strong benefits, but there are also some drawbacks to a cat door.

• It's a permanent modification to a home; you're literally cutting a hole in a door! This can be lease-breaking if you're renting, and can require a replacement door if you move out or want to sell the home later.
• Anything as small as or smaller than your cat can use the door as well (with some exceptions we'll talk about later.) This can allow access to pests and rodents that otherwise might not go through the door.
• It's a source of drafts. If you live in a climate where heat or cold is an issue and HVAC is a concern, a cat door can be a significant cost in your energy bills.

And, of course, if you're installing the door to an outdoor space, everything I mentioned above is true. I definitely don't recommend it! Always install a cat door between interior spaces or between enclosed spaces like a catio or a screened-in porch.

Picking the Type of Cat Door

If you've decided you want a cat door, you have to pick what kind of cat door to install. Basically, there are three choices to make.

The first is the size. Smaller cat doors work for smaller cats and keep out larger animals, but that can also include larger cats (if you have an obese cat like in the video I linked in the intro) or small dogs. Middle-sized doors are better for larger cats and larger breeds. There are also doggy doors that are large enough for even larger breeds of dogs – though not the largest like mastiffs – and can still work for cats. Generally, you want the smallest door you can get away with to avoid the issues in the cons list above.

The second is the material you're installing the door in. There are cat doors that are meant to be installed in wooden doors, but there are also cat doors that work for metal doors and even glass doors or windows. Those can be a lot harder to install, so you may need professional assistance rather than a DIY installation process.

The third is if you want a door with added features. You can get cat doors that are better insulated to help minimize the issues with drafts and climate access. You can also get cat doors that can be locked if you want to secure your cat in or out. One of the most convenient options is a cat door that responds to a microchip and only opens for specific animals, so if you have a cat and a nugget-seeking small dog, you can program it to open only for the cat. Some cat doors can even be programmed with a "curfew" to disallow access after a certain time of day.

Obviously, the more technologically advanced the cat door, the more maintenance it will require. Keep that in mind!

Installing a Cat Door

When installing a cat door, the first step is to decide if you're going to install it in a door or window you currently have or in something new. Often, especially if you have a historic old solid wood door, cutting a hole in it can feel terrible – and potentially hurt the value of your home if you choose to sell later. It can be a good idea to remove the good door and store it somewhere safe, and buy a new, cheaper door to put the cat door in. In some cases, you can even get a door with a cat door pre-installed, which saves you all of the work!

Note that if you want to install a cat door in a glass door or window, it's a good idea to call a professional glazier. Cutting a hole in glass is very tricky, and if you do it wrong, you shatter the entire pane, which isn't just a huge hassle; it can be very dangerous! I highly recommend not trying to install a cat door in glass on your own.

In wood, it's pretty easy. Mark out the dimensions of the cat door in an appropriate position. Generally, you want the top of the flap to be about an inch above the top of your cat's back for adequate spacing and enough of a ridge at the bottom that they step over but don't have to stretch to do it. Mark this out with a pencil on the door, and use whatever tools you need to cut the hole.

For solid wood doors, you'll likely need to drill the corners and then use a saw of some kind to cut along the edges. For hollow core doors, you may be able to cut them with something as simple as a utility knife since they tend to be little more than veneer and cardboard.

Generally, the cat door you buy will have instructions on how to install it specifically. There may be a rim to install first, there may be wires to run, it all depends. Just follow the instructions for your situation!

Training Your Cat to Use the Cat Door

Once the cat door is installed, you have to train your cat to use it. A younger, more inquisitive cat will likely take right to it, exploring and, when they aren't prevented from doing so, figuring it out right away. Otherwise, you'll need to use some positive reinforcement training.

The process is pretty simple. Close the main door so that the cat door is in between you and your cat. Have treats on hand, and call your cat to you. If the cat door's flap is transparent, hold the treat where they can see it. Make sure it's something they can smell regardless.

For very reticent cats, you may need to push open the cat door with one hand and hold the treat in the space with the other. The goal is to teach your cat that there's a gap there that they can make it through, drawing them through with the treat. With enough repetitions, they'll eventually get the idea.

There are also a few other tips you can try to ease the transition.

• Try adding your cat's scent to the door. Gently wipe down your cat with a towel and then rub that towel over the cat door so they feel more familiar with it.
• Prop or hold the flap open for a while, so they get used to it just being an open hole they can pass through.
• Sit on the far side of the cat door (if possible; a catio is probably too small for you) and hold the flap open so they can see you calling to them.

Ideally, it won't take long for your cat to learn that they can come and go as they please through the cat door, and you'll be good to go from there.

Have you ever tried to teach a cat to go through a cat door? What kinds of issues did you encounter, and how did you solve them? Let me know in the comments below! You know I love hearing stories of all your fur babies!